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Ubuntu 24.04 LTS must be configured to use TCP syncookies.

Overview

Finding IDVersionRule IDIA ControlsSeverity
V-270753UBTU-24-600190SV-270753r1066748_ruleCCI-001095medium
Description
Denial of service (DoS) occurs when a resource is not available for legitimate users, resulting in the organization not being able to accomplish its mission or causing it to operate at degraded capacity. Managing excess capacity ensures sufficient capacity is available to counter flooding attacks. Employing increased capacity and service redundancy may reduce the susceptibility to some DoS attacks. Managing excess capacity may include, for example, establishing selected usage priorities, quotas, or partitioning.
STIGDate
Canonical Ubuntu 24.04 LTS Security Technical Implementation Guide2026-05-14

Related Frameworks

1 mapping across 4 frameworks
SCF0 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (2) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

CAP-02Resource Priority
0.50
CAP-03Capacity Planning
0.50
NIST 800-530 mappings

No source states a mapping between these directly.

Also reachable in 2 hops (13) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

AC-17(10)Authenticate Remote Commands
1.00
AC-17(9)Disconnect or Disable Access
1.00
AC-3Access Enforcement
1.00
AC-4Information Flow Enforcement
1.00
AU-3Content of Audit Records
1.00
CM-6Configuration Settings
1.00
CM-7Least Functionality
1.00
CM-7(2)Prevent Program Execution
1.00
SC-47Alternate Communications Paths
1.00
SC-5Denial-of-service Protection
1.00

+3 more (top 10 by confidence shown)

CCI1 mapping
CCI-001095
1.00
NIST CSF 2.00 mappings

No source states a mapping between these directly.

Also reachable in 4 hops (1) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

PR.IR-04
0.50

Details

Check Text (C-270753r1066748_chk)

Verify Ubuntu 24.04 LTS is configured to use TCP syncookies with the following command: $ sysctl net.ipv4.tcp_syncookies net.ipv4.tcp_syncookies = 1 If the value is not "1", this is a finding. Check the saved value of TCP syncookies with the following command: $ sudo grep -ir net.ipv4.tcp_syncookies /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf 2> /dev/null /etc/sysctl.d/99-sysctl.conf:net.ipv4.tcp_syncookies=1 /etc/sysctl.conf:net.ipv4.tcp_syncookies=1 If the "net.ipv4.tcp_syncookies" option is not set to "1", is commented out, or is missing, this is a finding.

Fix Text (F-74687r1066747_fix)

Configure Ubuntu 24.04 LTS to use TCP syncookies with the following command: $ sudo sysctl -w net.ipv4.tcp_syncookies=1 If "1" is not the system's default value, add or update the following line in "/etc/sysctl.conf": net.ipv4.tcp_syncookies = 1